Lab: A serverless API (API Gateway, Lambda, DynamoDB) on LocalStack

What you will learn in this TP

• Design a DynamoDB table
• Deploy a Lambda function
• Expose a function through API Gateway

Introduction #

What you will learn in this section

• Design a DynamoDB table
• Deploy a Lambda function
• Expose a function through API Gateway

Context. An internal service must store and read orders. You build a serverless API that costs nothing when idle.

Prerequisites: Docker, the AWS CLI and LocalStack (pip install localstack awscli-local terraform-local): everything runs locally, with no AWS account or charges  ·  Estimated time: 60 min

An API that creates and reads orders in DynamoDB.

Hands-on #

Guided steps, with their solution.

1. 1. Create the table

   Why? The partition key spreads data; here an order is read by its identifier.

   Create the commandes table (key id, on-demand billing).

2. 2. Write and deploy the function

   Why? The function reads the HTTP method from the API Gateway event and acts on the table.

   Write app.py (POST creates an order, GET reads it), zip it and create the function.

3. 3. Expose through an HTTP API

   Why? API Gateway routes HTTP requests to the function.

   Create an HTTP API with POST /commandes and GET /commandes/{id} routes integrated with the function.

4. 4. Test and observe

   Why? Function logs reach CloudWatch Logs, just as on AWS.

   Create an order, read it back, request an unknown id and check the logs.

Difficulty level : ●●●○○ (3/5)